1. Field of the Invention
The present invention relates to a touch screen panel, and more particularly, to a touch screen panel which is capable of sensing an exact position touched by a user or instrument, or a pressured applied to the touched position.
2. Discussion of the Related Art
A touch screen can perform a predetermined function by detecting a letter or location on a display screen when it is touched by a user's hand or passive object.
Generally, the touch screen is classified into a resistive type, a capacitive type, an infrared ray type (hereinafter, referred to as “IR type”), and a surface acoustic wave type (hereinafter, referred to as “SAW type”).
The resistive type touch screen is comprised of two substrates bonded to each other, wherein each substrate is coated with a transparent electrode. If a predetermined pressure is applied to a predetermined portion of the resistive type touch screen by a finger or pen, the two substrates are electrically connected at the predetermined touched portion through a contact of the two substrates at the predetermined touched portion. However, the resistive type touch screen has a problem of low light transmittance. In order to overcome this problem of low light transmittance, it is necessary for the resistive type touch screen to provide the more luminous screen. This requires an addition power, whereby battery efficiency becomes lowered. Also, since the two electrodes provided in the respective substrates have to be in contact by pressing the surface of the resistive type touch screen through the use of finger or pen, the resistive type touch screen has a problem of low endurance.
The capacitive type touch screen is operated by sensing a static electricity from human's body. However, the capacitive type touch screen is high-priced. In addition, the capacitive type touch screen does not work with a gloved finger or stylus pen.
The IR type touch screen using straightness of infrared rays can determine a touched portion according as a signal is not detected due to a cutoff by the finger or pen. However, the contaminated surface of IR type touch screen may cause a malfunction thereof. Also, the IR type touch screen necessarily requires an additional component such as a lens so as to obtain collimated beams.
The SAW type touch panel uses ultrasonic waves. That is, if the finger is touched on a predetermined portion of panel, some of the ultrasonic waves are absorbed into the touched portion. The SAW type touch panel can detect the touched portion through the decreased ultrasonic waves. Like the IR type touch screen, the contaminated surface of SAW type touch screen may cause a malfunction thereof. In addition, the SAW type touch screen does not work with a gloved finger or stylus pen.